2,484. Shechita in the Oral Law

Hilchos Shechita 1:3

One need not slaughter fish and locusts; rather, the act of gathering them renders them permitted for consumption as per Numbers 11:22, “Could enough sheep and cattle be slaughtered for them? If all the fish of the sea were gathered for them….” We see that gathering fish is compared to slaughtering livestock. As far as locusts, Isaiah 33:4 refers to gathering locusts, from which we infer that gathering is sufficient. Therefore, if fish die in the water, they are permitted, and they may also be eaten while still alive.

Hilchos Shechita 1:4

The Torah doesn’t give the details for ritual slaughter so we must discuss: the proper place on the animal to perform shechita; its measure; the implement to be used; when we slaughter; where we slaughter; how we slaughter; what invalidates shechita; who can perform shechita. We were commanded regarding these things in Deuteronomy 12:21, “You shall slaughter from your cattle... as I commanded you.” The details were communicated to us orally along with the rest of the Oral Law. The Oral Law is called “the mitzvah” (in Exodus 24:12) as the Rambam explained in his introduction to the Mishneh Torah.